Phosphophyllite
| Phosphophyllite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Fe [6] Zn 2 [4] [PO 4 ] 2 • 4H 2 O |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.CA.40 ( 8th edition : VII / C.11) 02/40/07/01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | P 2 1 / c (No. 14) |
| Lattice parameters |
a = 10.38 Å ; b = 5.08 Å; c = 10.55 Å β = 121.1 ° |
| Formula units | Z = 2 |
| Frequent crystal faces | {110}, {011}, { 1 02}, {111}, { 3 11} |
| Twinning | common to {100}, contact twins ( fishtail ), pervasive and polysynthetic twins |
| Physical Properties | |
| Mohs hardness | 3 to 3.5 |
| Density (g / cm 3 ) | measured: 3.08 to 3.13; calculated: 3.12 |
| Cleavage | completely after {100}, clearly after { 1 02} |
| Break ; Tenacity | brittle |
| colour | light bluish green, sea green, colorless |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.595 to 1.599 n β = 1.614 to 1.617 n γ = 1.616 to 1.620 |
| Birefringence | δ = 0.021 |
| Optical character | biaxial negative |
| Axis angle | 2V = 44 ° (measured); 34 ° (calculated) |
Phosphophyllite is a rarely occurring mineral from the mineral class of "phosphates, arsenates and vanadates". It crystallizes in the monoclinic crystal system with the idealized chemical composition Fe [6] Zn 2 [4] [PO 4 ] 2 · 4H 2 O and is therefore, chemically speaking, a water-containing iron - zinc - phosphate .
Phosphophyllite usually develops thick tabular crystals and contact twins with a "fishtail" or "swallowtail" -like habit of several centimeters in length. The transparent to translucent crystals are light bluish green to sea green in color with a white line color and have a glass-like sheen on the surfaces . Colorless phosphophyllites are also rarely found.
Etymology and history
Phosphophyllite was first discovered in the Hagendorf-Nord mine (Meixner mine) near Hagendorf (municipality of Waidhaus ) in Upper Palatinate (Bavaria) and described in 1920 by Heinrich Laubmann and Hermann Steinmetz, who used the ancient Greek word for the mineral based on its phosphate content and crystal shape φύλλον [phýllon] for "leaf".
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the phosphophyllite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates without foreign anions ", where together with barahonaite (Al ) , Barahonait- (Fe) , Fahleit , hopeite , Parahopeit , Radovanit and Smolianinovit the "Hopeit-Parahopeit group" with the system number. VII / C.11 formed.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns phosphophyllite to the category of “phosphates etc. without additional anions; with H 2 O “. This, however, is further divided according to the relative size of the participating cations , so that the mineral according to its composition in the subsection "With large and small / medium-sized cations" is to find where it is the only member of the unnamed group 8.CA.40 forms .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns phosphophyllite to the class of "phosphates, arsenates and vanadates" and there in the department of "water-containing phosphates, etc.". Here he is to be found as the only member of the unnamed group 02/40/07 within the sub-section “Water-containing phosphates etc., with A 2+ (B 2+ ) 2 (XO 4 ) × x (H 2 O)”.
Crystal structure
Phosphophyllite crystallizes monoclinically in the space group P 2 1 / c (space group no. 14) with the lattice parameters a = 10.38 Å ; b = 5.08 Å; c = 10.55 Å and β = 121.1 ° as well as two formula units per unit cell .
properties
Some phosphophyllites show a violet fluorescence under UV light .
Education and Locations
Phosphophyllit formed secondarily by weathering primary phosphates in the oxidation zone of ore - deposits and in granite pegmatite . Various apatites , fairfieldite , phosphosiderite , rockbridgeite , sphalerite , strictite , triplite , triphyline and vivianite can occur as accompanying minerals .
As a rare mineral formation, phosphosphyllite could only be detected at a few sites, although around 30 sites are known to date (as of 2014). In addition to its type locality Hagendorf-Nord in Bavaria, the mineral has so far only been found in Germany on the slag heaps of the zinc smelter Münsterbusch in the Aachen district in North Rhine-Westphalia.
The Unificada Mine at Cerro Rico (also Cerro de Potosí ) in the Bolivian Department of Potosí, where perfect crystals of up to 14 centimeters in diameter have been found, is known for its unusual phosphophyllite finds.
Other previously known sites include Reaphook Hill in the Flinders Range in South Australia, the Morococala Mine near Santa Fe and the Huallani Mine in the canton of Machacamarca in Bolivia, the East Kemptville tin mine near Argyle (Yarmouth County) in the Canadian province of Nova Scotia , a mica quarry near Norrö in the Swedish region of Södermanland , the Kabwe mine (Broken Hill Mine) in the central province of Zambia, Přibyslavice in Okres Kutná Hora ( Kuttenberg ) in the Czech Republic and various locations in several states in the USA.
use
Despite its often clear and shiny crystals of aquamarine-like color, phosphophyllite is not used as a gemstone because it would scratch quickly when worn due to its low Mohs hardness. For collectors, however, it is occasionally offered in different facet cuts.
See also
literature
- H. Laubmann, H. Steinmetz: Phosphate-bearing pegmatites of the Upper Palatinate and Bavarian Forest. In: Journal for Crystallography and Mineralogy. Volume 55, 1920, pp. 523-586 ( PDF; 4.1 MB ).
- W. Kleber, F. Liebau, E. Piatkowiak: On the structure of the phosphophyllite Zn 2 Fe [PO 4 ] 2 , 4H 2 O. In: Acta Crystallographica. Volume 14, 1961, pp. 795-795.
- RJ Hill: The crystal structure of phosphophyllite. In: American Mineralogist. Volume 62, 1977, pp. 812-817 ( PDF; 621.5 kB ).
Web links
- Mineral Atlas: Phosphophyllite (Wiki)
- Database-of-Raman-spectroscopy - Phosphophyllite
- American-Mineralogist-Crystal-Structure-Database - Phosphophyllite
- realgems.org - Phosphophyllite (with picture examples of polished phosphophyllites)
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 473 .
- ↑ Webmineral - Phosphophyllite
- ↑ a b c Phosphophyllite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF; 64.7 kB ) .
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 5th completely revised and supplemented edition. Weise, Munich 2008, ISBN 978-3-921656-70-9 .
- ↑ a b c d Mindat - Phosphophyllite
- ^ Walter Schumann: Precious stones and gemstones. All species and varieties in the world. 1600 unique pieces . 13th revised and expanded edition. BLV Verlags-GmbH., Munich a. a. 2002, ISBN 3-405-16332-3 , pp. 57 .
- ↑ Mindat - Number of locations for phosphophyllite
- ↑ Petr Korbel, Milan Novák: Mineral Encyclopedia . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 ( Dörfler Natur ).
- ↑ Find location list for phosphophyllite in the Mineralienatlas and Mindat
- ^ Walter Schumann: Precious stones and gemstones. All species and varieties in the world. 1600 unique pieces . 13th revised and expanded edition. BLV Verlags-GmbH., Munich a. a. 2002, ISBN 3-405-16332-3 , pp. 226 .